A Oracle Database JSON Restrictions

The restrictions associated with Oracle support of JSON data in Oracle Database are listed here.

Unless otherwise specified, an error is raised if a specified limitation is not respected.

  • General

    • Number of nesting levels for a JSON object or array: 1000, maximum.

    • JSON field name length: 32767 bytes, maximum.

  • SQL/JSON functions

    • Return-value length: 32767 bytes, maximum.

    • Path length: 4K bytes, maximum.

    • Number of path steps: 65535, maximum.

  • Simplified JSON syntax

    • Path length: 4K bytes, maximum.

    • Path component length: 128 bytes, maximum.

  • JSON search index

    • Field name length: 255 bytes, maximum. If a document has a field name longer than 255 bytes then it might not be completely indexed. In that case, an error is recorded in database view CTX_USER_INDEX_ERRORS.


      You must rebuild any JSON search indexes and Oracle Text indexes created prior to Oracle Database 18c if they index JSON data that contains object fields with names longer than 64 bytes. See Oracle Database Upgrade Guide for more information.

  • JSON data guide

    • Path length: 4000 bytes, maximum. A path longer than 4000 bytes is ignored by a data guide.

    • Number of children under a parent node: 1024, maximum. A node that has more than 1024 children is ignored by a data guide.

    • Field value length: 32767 bytes. If a JSON field has a value longer than 32767 bytes then the data guide reports the length as 32767.

    • Zero-length field name: A zero-length (empty) object field name ("") is not supported for use with JSON data guide. Data-guide behavior is undefined for JSON data that contains such a name.

  • OSON

    • All field names, total size: 65535 bytes, maximum.

    • Field name length (each): 255 bytes, maximum.

    • No duplicate fields: If a JSON object with duplicate field names is represented using OSON then only one of these fields is present (kept).

  • PL/SQL getter method JSON_OBJECT_T.get_keys() returns at most 32767 field names for a given JSON object. An error is raised if it is applied to an object with more than 32767 fields.